Shotcrete is concrete that is pneumatically projected at high velocity onto a surface. Shotcrete is typically classified into two categories:
-wet mix process: concrete is batched, delivered to site, and pumped to the shotcrete nozzle where compressed air is added to the flowing material just prior to shooting.
-dry mix process: concrete ingredients excluding water are mixed and delivered to the shotcrete nozzle using compressed air. Water is added to the dry materials at the nozzle, just prior to shooting.
Structural shotcrete is typically completed using a wet mix process however, for remote areas or limited quantities, dry mix may be considered due to its versatility and lack of reliance on the availability of ready mix concrete.